Liquid crystal composition and liquid crystal display device

ABSTRACT

A liquid crystal composition having a negative dielectric anisotropy that includes two components, wherein the first component is at least one compound selected from the group of compounds represented by formulas (1-1) and (1-2), and the second component is at least one compound selected from the group of compounds represented by formulas (2-1) to (2-3): 
                         
wherein, for example, R 1 , R 2 , R 3  and R 4  are each alkyl having 1 to 12 carbons; X 1  and X 2  are each fluorine; ring A, ring B, ring C, ring D, ring E, ring F and ring G are each 1,4-cyclohexylene or 1,4-phenylene; and Z 1  is a single bond.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Japanese PatentApplication No. JP 2007-237151, filed Sep. 12, 2007 and Japanese PatentApplication No. JP 2008-102509, filed Apr. 10, 2008, which is expresslyincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a liquid crystal composition suitable for usein an active matrix (AM) device, and an AM device containing thecomposition. More specifically, the invention relates to a liquidcrystal composition having a negative dielectric anisotropy, and alsorelates to a device of an in-plane switching (IPS) mode, a verticalalignment (VA) mode or a polymer sustained alignment (PSA) mode,containing the composition.

2. Related Art

In a liquid crystal display device, classification based on an operatingmode of liquid crystals includes phase change (PC), twisted nematic(TN), super twisted nematic (STN), electrically controlled birefringence(ECB), optically compensated bend (OCB), in-plane switching (IPS),vertical alignment (VA), a polymer sustained alignment (PSA) mode and soforth. Classification based on a driving mode of the device includes apassive matrix (PM) and an active matrix (AM). PM is further classifiedinto static, multiplex and so forth, and AM is classified into a thinfilm transistor (TFT), a metal insulator metal (MIM) and so forth. TFTis further classified into amorphous silicon and polycrystal silicon.The latter is classified into a high temperature type and a lowtemperature type according to a production process. Classification basedon a light source includes a reflection type utilizing a natural light,a transmission type utilizing a backlight and a semi-transmission typeutilizing both the natural light and the backlight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to obtainan AM device having good general characteristics. Table 1 belowsummarizes a relationship between the general characteristics of thetwo. The general characteristics of the composition will be explainedfurther based on a commercially available AM device. A temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase isapproximately 70° C. or more and a desirable minimum temperature thereofis approximately −10° C. or less. The viscosity of the compositionrelates to the response time of the device. A short response time isdesirable for displaying a moving image with the device. Accordingly, asmall viscosity of the composition is desirable. A small viscosity at alow temperature is more desirable.

TABLE 1 General Characteristics of Liquid Crystal Composition and AMDevice General Characteristics of an AM No General Characteristics of aComposition Device 1 Temperature range of a nematic phase Usabletemperature range is wide is wide 2 Viscosity is small¹⁾ Response timeis short 3 Optical anisotropy is suitable Contrast ratio is large 4Dielectric anisotropy is positively or Threshold voltage is low,electric power negatively large consumption is small and contrast ratiois large 5 Specific resistance is large Voltage holding ratio is largeand a contrast ratio is large 6 It is stable to ultraviolet light andheat Service life is long ¹⁾A liquid crystal composition can be injectedinto a cell in a short time.

The optical anisotropy of the composition relates to the contrast ratioof the device. A product (Δn·d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed to maximizethe contrast ratio. A suitable value of the product depends on the kindof operation mode. In a device having a VA mode, a suitable value is ina range of from approximately 0.30 to approximately 0.40 μm, and in adevice having an IPS mode, a suitable value is in a range of fromapproximately 0.20 approximately to 0.30 μm. In this case, a compositionhaving a large optical anisotropy is desirable for a device having asmall cell gap. A large dielectric anisotropy of the compositioncontributes to a low threshold voltage, a small electric powerconsumption and a large contrast ratio. Accordingly, a large dielectricanisotropy is desirable. A large specific resistance of the compositioncontributes to a large voltage holding ratio and a large contrast ratioof the device. Accordingly, a composition having a large specificresistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. A stability of thecomposition to an ultraviolet light and heat relates to a service lifeof the liquid crystal display device. In the case where the stability ishigh, the device has a long service life. These characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

In an AM device having a TN mode, a composition having a positivedielectric anisotropy is used. In an AM device having a VA mode, acomposition having a negative dielectric anisotropy is used. In an AMdevice having an IPS mode, a composition having a positive or negativedielectric anisotropy is used. In an AM device having a PSA mode, acomposition having a positive or negative dielectric anisotropy is used.A liquid crystal composition having a negative dielectric anisotropy isdisclosed in the following document.

Conventional compositions are disclosed in JP H10-237004 A/1998 and JP2007-002132 A/2007.

A desirable AM device is characterized as having a usable temperaturerange that is wide, a response time that is short, a contrast ratio thatis large, a threshold voltage that is low, a voltage holding ratio thatis large, a service life that is long, and so forth. Even onemillisecond shorter response time is desirable. Thus, the compositionhaving characteristics such as a high maximum temperature of a nematicphase, a low minimum temperature of a nematic phase, a small viscosity,a large optical anisotropy, a large dielectric anisotropy, a largespecific resistance, a high stability to an ultraviolet light, a highstability to heat, and so forth is especially desirable.

SUMMARY OF THE INVENTION

The invention concerns a liquid crystal composition having a negativedielectric anisotropy that includes two components, wherein the firstcomponent is at least one compound selected from the group of compoundsrepresented by formulas (1-1) and (1-2), and the second component is atleast one compound selected from the group of compounds represented byformulas (2-1) to (2-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; R³ andR⁴ are each independently alkyl having 1 to 12 carbons or alkenyl having2 to 12 carbons, provided that in the alkyl and the alkenyl, arbitraryhydrogen may be replaced by fluorine, and arbitrary —CH₂— may bereplaced by —O—; X¹ and X² are each independently fluorine or chlorine;ring A, ring B, ring C and ring D are each independently1,4-cyclohexylene or 1,4-phenylene; ring E and ring G are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene; ring F is 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; and Z¹ is a single bond or carbonyloxy.

The invention also concerns a liquid crystal display device thatincludes the liquid crystal composition, and so forth.

DETAILED DESCRIPTION OF THE INVENTION

The terms used in the specification and claims are defined as follows.The liquid crystal composition and/or the liquid crystal display deviceof the invention may occasionally be expressed simply as “thecomposition” or “the device,” respectively. A liquid crystal displaydevice is a generic term for a liquid crystal display panel and a liquidcrystal display module. The “liquid crystal compound” is a generic termfor a compound having a liquid crystal phase such as a nematic phase, asmectic phase and so forth, and also for a compound having no liquidcrystal phase but being useful as a component of a composition. Theuseful compound contains, for example, a 6-membered ring such as1,4-cyclohexylene and 1,4-phenylene, and a rod like molecular structure.An optically active compound or a polymerizable compound mayoccasionally be added to the composition. Even in the case where thecompound is a liquid crystal compound, the compound is classified intoan additive. At least one compound selected from a group of compoundsrepresented by formula (1) may be abbreviated to “the compound (1).” The“compound (1)” means one compound or two or more compounds representedby formula (1). The other formulas are applied with the same rules. Theterm “arbitrary” means that not only the position but also the numberare arbitrary, but the case where the number is zero is not included.

A higher limit of a temperature range of a nematic phase may beabbreviated to “a maximum temperature.” A lower limit of a temperaturerange of a nematic phase may be abbreviated to “a minimum temperature.”“A specific resistance is large” means that the composition has a largespecific resistance at room temperature and also at a high temperaturein the initial stage, the composition has a large specific resistance atroom temperature and also at a high temperature even after it has beenused for a long time. “A voltage holding ratio is large” means that adevice has a large voltage holding ratio at room temperature and also ata high temperature in the initial stage, the device has a large voltageholding ratio at room temperature and also at a high temperature evenafter it has been used for a long time. In the description of thecharacteristics such as optical anisotropy, the characteristics of thecomposition such as the optical anisotropy and so forth are valuesmeasured in the methods disclosed in Examples. The first componentincludes one compound or two or more compounds. “A ratio of the firstcomponent” means the percentage by weight (% by weight) of the firstcomponent based on the total weight of liquid crystal composition. Aratio of the second component and so forth are applied with the samerule. A ratio of an additive mixed with the composition means thepercentage by weight (% by weight) based on the total weight of liquidcrystal composition.

In the chemical formulas of the component compounds, symbol R¹ is usedin plural compounds. In these compounds, plural R¹ may be the same as ordifferent from each other. In one case, for example, R¹ of the compound(1) is ethyl and R¹ of the compound (2) is ethyl. In another case, R¹ ofthe compound (1) is ethyl and R¹ of the compound (2) is propyl. Thisrule is also applicable to the symbols R², R³ and so forth.

One of the advantages of the invention is to provide a liquid crystalcomposition that satisfies many characteristics among thecharacteristics such as a high maximum temperature of a nematic phase, alow minimum temperature of a nematic phase, a small viscosity, a largeoptical anisotropy, a large negative dielectric anisotropy, a largespecific resistance, a high stability to ultraviolet light and a highstability to heat. Another of the advantages of the invention is toprovide a liquid crystal composition that is properly balanced regardingmany characteristics. Another of the advantages of the invention is toprovide a liquid crystal display device that contains the liquid crystalcomposition. One aspect of the invention is to provide a liquid crystalcomposition that has a large optical anisotropy, a large negativedielectric anisotropy, a high stability to ultraviolet light and soforth, and is to provide an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

The Invention has the Following Features.

1. A liquid crystal composition having a negative dielectric anisotropycomprising two components, wherein the first component is at least onecompound selected from the group of compounds represented by formulas(1-1) and (1-2), and the second component is at least one compoundselected from the group of compounds represented by formulas (2-1) to(2-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; R³ andR⁴ are each independently alkyl having 1 to 12 carbons or alkenyl having2 to 12 carbons, provided that in the alkyl and the alkenyl, arbitraryhydrogen may be replaced by fluorine, and arbitrary —CH₂— may bereplaced by —O—; X¹ and X² are each independently fluorine or chlorine;ring A, ring B, ring C and ring D are each independently1,4-cyclohexylene or 1,4-phenylene; ring E and ring G are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene; ring F is 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; and Z¹ is a single bond or carbonyloxy.

2. The liquid crystal composition according to item 1, wherein the firstcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (1-1) and at least one compoundselected from the group of compounds represented by formula (1-2), andthe second component is at least one compound selected from the group ofcompounds represented by formula (2-1).

3. The liquid crystal composition according to item 1, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-2).

4. The liquid crystal composition according to item 1, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-1) and at least onecompound selected from the group of compounds represented by formula(2-3).

5. The liquid crystal composition according to item 1, wherein thesecond component is a mixture of at least one compound selected from thegroup of compounds represented by formula (2-2) and at least onecompound selected from the group of compounds represented by formula(2-3).

6. The liquid crystal composition according to any one of items 1 to 5,wherein a ratio of the first component is from approximately 5% byweight to approximately 50% by weight, and a ratio of the secondcomponent is from approximately 35% by weight to approximately 70% byweight, based on the total weight of the liquid crystal composition.

7. The liquid crystal composition according to any one of items 1 to 6,wherein the composition further comprises at least one compound selectedfrom the group of compounds represented by formula (3) as a thirdcomponent:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring Iis independently 1,4-cyclohexylene or 1,4-phenylene; Z² is a singlebond, ethylene, carbonyloxy or methyleneoxy; X³ and X⁴ are eachindependently fluorine or chlorine; and n is 1 or 2.

8. The liquid crystal composition according to item 7, wherein the thirdcomponent is at least one compound selected from the group of compoundsrepresented by formulas (3-1) to (3-12):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.

9. The liquid crystal composition according to item 7, wherein the thirdcomponent is a mixture of at least one compound selected from the groupof compounds represented by formula (3-1) and at least one compoundselected from the group of compounds represented by formula (3-7).

10. The liquid crystal composition according to item 7, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-1) and at least onecompound selected from the group of compounds represented by formula(3-9).

11. The liquid crystal composition according to item 7, wherein thethird component is a mixture of at least one compound selected from thegroup of compounds represented by formula (3-4) and at least onecompound selected from the group of compounds represented by formula(3-9).

12. The liquid crystal composition according to any one of items 7 to11, wherein a ratio of the first component is from approximately 5% byweight to approximately 50% by weight, a ratio of the second componentis from approximately 35% by weight to approximately 70% by weight, anda ratio of the third component is from approximately 5% by weight toapproximately 40% by weight, based on the total weight of the liquidcrystal composition.

13. The liquid crystal composition according to any one of items 1 to12, wherein the composition has a maximum temperature of a nematic phaseof approximately 70° C. or more, an optical anisotropy (25° C.) at awavelength of 589 nm of approximately 0.08 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately −2 or less.

14. A liquid crystal display device that includes the liquid crystalcomposition according to any one of items 1 to 13.

15. The liquid crystal display device according to item 14, wherein theliquid crystal display device has an operation mode of a VA mode or anIPS mode, and has a driving mode of an active matrix mode.

16. The liquid crystal display device according to item 14, wherein theliquid crystal display device has an operation mode of a PSA mode, andhas a driving mode of an active matrix mode.

The invention further includes: (1) the composition described above,wherein the composition further contains an optically active compound;(2) the composition described above, wherein the composition furthercontains an additive, such as an antioxidant, an ultraviolet lightabsorbent, a defoaming agent, a polymerizable compound and/or apolymerization initiator; (3) an AM device containing the compositiondescribed above; (4) a device having a TN, ECB, OCB, IPS, VA or PSAmode, containing the composition described above; (5) a device of atransmission type, containing the composition described above; (6) useof the composition described above as a composition having a nematicphase; and (7) use as an optically active composition by adding anoptically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, the main characteristics of the componentcompounds and the main effects of the compounds on the composition willbe explained. Third, desirable ratios of the component compounds and thebasis thereof will be explained. Fourth, a desirable embodiment of thecomponent compounds will be explained. Fifth, examples of the componentcompound will be shown. Sixth, additives that may be added to thecomposition will be explained. Seventh, the preparation methods of thecomponent compound will be explained. Lastly, use of the compositionwill be explained.

First, the constitution of component compounds in the composition willbe explained. The composition of the invention is classified into thecomposition A and the composition B. The composition A may furthercontain other compounds such as another liquid crystal compound, anadditive, an impurity, and so forth. This liquid crystal compound isdifferent from the compound (1-1), the compound (1-2), the compound(2-1), the compound (2-2), the compound (2-3) and the compound (3). Sucha liquid crystal compound is mixed with the composition for the purposeof adjusting the characteristics of the composition. Among the liquidcrystal compounds, an amount of a cyano compound is desirably small fromthe viewpoint of stability to heat or ultraviolet light. The amount of acyano compound is more desirably approximately 0% by weight. Theadditive includes an optically active compound, an antioxidant, anultraviolet light absorbent, a coloring matter, a defoaming agent, apolymerizable compound, a polymerization initiator and so forth. Theimpurity is a compound and so forth contaminated in the process such asthe synthesis of a component compound and so forth. This compound isclassified into an impurity even when the compound is a liquid crystalcompound.

The composition B essentially consists of the compounds selected fromthe compound (1-1), the compound (1-2), the compound (2-1), the compound(2-2), the compound (2-3) and the compound (3). The term “essentially”means that the composition does not contain a liquid crystal compoundwhich is different from these compounds. The term “essentially” alsomeans that the composition may further contain the additive, theimpurity, and so forth. The components of the composition B are fewerthan those of the composition A. The composition B is preferable to thecomposition A from the viewpoint of costs. The composition A ispreferable to the composition B, because characteristics of thecomposition A can be further adjusted by mixing with other liquidcrystal compounds.

Second, the main characteristics of the component compounds and the maineffects of the compounds on the composition will be explained. The maincharacteristics of the component compounds are summarized in Table 2. InTable 2, the symbol L represents large or high, the symbol M representsa middle degree, and the symbol S represents small or low. The symbolsL, M and S are classification based on qualitative comparison among thecomponent compounds.

TABLE 2 Characteristics of Compounds Compound (1-1) (1-2) (2-1) (2-2)(2-3) (3) Maximum S M S M L S-M temperature Viscosity M-L M-L S S-M MM-L Optical M M-L S-M S-L M-L M-L anisotropy Dielectric M-L¹⁾ M-L¹⁾ S SS M-L¹⁾ anisotropy Specific L L L L L L resistance ¹⁾A value ofdielectric anisotropy is negative, and the symbols show magnitude ofabsolute values.

The main effects of the component compounds to the characteristics ofthe composition upon mixing the component compounds to the compositionare as follows. The compound (1-1) increases the absolute value of thedielectric anisotropy. The compound (1-2) increases the absolute valueof the dielectric anisotropy and increases the maximum temperature. Thecompound (2-1) decreases the viscosity. The compound (2-2) decreases theminimum temperature and decreases the viscosity. The compound (2-3)increases the maximum temperature, increases the optical anisotropy anddecreases the viscosity. The compound (3) decreases the minimumtemperature and increases the absolute value of the dielectricanisotropy.

Third, desirable ratios of the component compounds and the basistherefor will be explained. A desirable ratio of the first component isapproximately 5% by weight or more for increasing the absolute value ofthe dielectric anisotropy, and is approximately 50% by weight or lessfor decreasing the minimum temperature. A more desirable ratio is fromapproximately 10% by weight to approximately 45% by weight. Aparticularly desirable ratio is from approximately 15% by weight toapproximately 45% by weight.

A desirable ratio of the second component is approximately 35% by weightor more for increasing the optical anisotropy and decreasing theviscosity, and is approximately 70% by weight or less for decreasing theminimum temperature. A more desirable ratio is from approximately 35% byweight to approximately 65% by weight. A particularly desirable ratio isfrom approximately 40% by weight to approximately 65% by weight.

In the case where the third component is used, a desirable ratio thereofis approximately 5% by weight or more for increasing the absolute valueof the dielectric anisotropy, and is approximately 40% by weight or lessfor decreasing the minimum temperature. A more desirable ratio is fromapproximately 5% by weight to approximately 35% by weight. Aparticularly desirable ratio is from approximately 10% by weight toapproximately 35% by weight.

Fourth, a desirable embodiment of the component compound will beexplained. R¹ and R² are each independently alkyl having 1 to 12carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12carbons. Desirable R¹ is alkyl having 1 to 12 carbons or alkenyl having2 to 12 carbons in order to decrease the minimum temperature and todecrease the viscosity. Desirable R² is alkoxy having 1 to 12 carbons inorder to increase the absolute value of the dielectric anisotropy. R³and R⁴ are each independently alkyl having 1 to 12 carbons or alkenylhaving 2 to 12 carbons, provided that in the alkyl and the alkenyl,arbitrary hydrogen may be replaced by fluorine, and arbitrary —CH₂— maybe replaced by —O—. Desirable R³ and R⁴ are each alkyl having 1 to 12carbons in order to enhance the stability to ultraviolet light or heat.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,or octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl, orheptyl for decreasing a viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy, or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing a viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl, or 3-pentenyl for decreasing aviscosity. A desirable configuration of —CH═CH— in these alkenylsdepends on the position of a double bond. Trans is desirable in thealkenyl such as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl,3-pentenyl, and 3-hexenyl for decreasing the viscosity. Cis is desirablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thesealkenyls, linear alkenyl is preferable to branched alkenyl.

Preferred examples of alkenyl in which arbitrary hydrogen is replaced byfluorine include 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More preferred examples thereof include2,2-difluorovinyl and 4,4-difluoro-3-butenyl for decreasing theviscosity.

Ring A, ring B, ring C and ring D are each independently1,4-cyclohexylene or 1,4-phenylene. Desirable ring A and ring B are each1,4-phenylene in order to increase the optical anisotropy. Desirablering C and ring D are each 1,4-cyclohexylene in order to increase themaximum temperature and to decrease the viscosity. Ring E and ring G areeach independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene. Desirable ring E andring G are each 1,4-cyclohexylene in order to increase the maximumtemperature and to decrease the viscosity. Ring F is 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene. Desirable ring F is 1,4-cyclohexylene inorder to increase the maximum temperature and to decrease the viscosity.Ring I is 1,4-cyclohexylene or 1,4-phenylene, and in the case where n is2, two rings I may be the same or different. Desirable ring I is1,4-cyclohexylene in order to increase the maximum temperature and todecrease the viscosity.

Z¹ is a single bond or carbonyloxy. Desirable Z¹ is a single bond inorder to decrease the viscosity. Z² is a single bond, ethylene,carbonyloxy or methyleneoxy. Desirable Z² is a single bond in order todecrease the viscosity.

X¹ and X² are each independently fluorine or chlorine. Desirable X¹ andX² are each fluorine in order to decrease the viscosity. X³ and X⁴ areeach independently fluorine or chlorine. Desirable X³ and X⁴ are eachfluorine in order to decrease the viscosity.

n is 1 or 2. Desirable n is 1 in order to decrease the minimumtemperature.

Fifth, examples of the component compounds will be shown. In thedesirable compounds described below, R⁵ and R⁶ are each independentlylinear alkyl having 1 to 12 carbons or linear alkenyl having 2 to 12carbons. R⁷ is linear alkyl having 1 to 12 carbons or linear alkoxyhaving 1 to 12 carbons. In these desirable compounds, trans ispreferable to cis for the configuration of 1,4-cyclohexylene forincreasing a maximum temperature.

Desirable compounds (1-1) are the compounds (1-1-1) to (1-1-8). Moredesirable compounds (1-1) are the compounds (1-1-1) to (1-1-5). Aparticularly desirable compound (1-1) is the compound (1-1-5). Desirablecompounds (1-2) are the compounds (1-2-1) to (1-2-16). More desirablecompounds (1-2) are the compounds (1-2-1), (1-2-5), (1-2-9) and(1-2-13). Particularly desirable compounds (1-2) are the compounds(1-2-1) and (1-2-13). Desirable compounds (2-1) are the compounds(2-1-1) to (2-1-3). A more desirable compound (2-1) is the compound(2-1-1). Desirable compounds (2-2) are the compounds (2-2-1) to (2-2-4).A more desirable compound (2-2) is the compound (2-2-1). Desirablecompounds (2-3) are the compounds (2-3-1) to (2-3-4). A more desirablecompound (2-3) is the compound (2-3-3). Desirable compounds (3) are thecompounds (3-1-1) to (3-12-1). More desirable compounds (3) are thecompounds (3-1-1) to (3-5-1), (3-7-1) to (3-9-1), (3-11-1) and (3-12-1).Particularly desirable compounds (3) are the compounds (3-1-1), (3-4-1),(3-7-1), (3-9-1) and (3-12-1).

Sixth, additives capable of being mixed with the composition will beexplained. The additives include an optically active compound, anantioxidant, an ultraviolet light absorbent, a coloring matter, adefoaming agent, a polymerizable compound, a polymerization initiatorand so forth. An optically active compound is mixed in the compositionfor inducing a helical structure of liquid crystal to provide a twistangle. Examples of the optically active compound include the compounds(4-1) to (4-4) below. A desirable ratio of the optically active compoundis approximately 5% by weight or less, and a more desirable ratiothereof ranges from approximately 0.01% by weight to approximately 2%.

An antioxidant is mixed with the composition in order to avoid adecrease in specific resistance caused by heating in the air, or tomaintain a large voltage holding ratio at room temperature and also at ahigh temperature even after the device has been used for a long time.

Preferred examples of the antioxidant include the compound (5):

wherein n is an integer of from 1 to 9. In the compound (5), desirable nare 1, 3, 5, 7, or 9. More desirable n are 1 or 7. When n is 1, thecompound (5) has a large volatility, and is effective in preventing thedecrease of specific resistance caused by heating in the air. When n is7, the compound (5) has a small volatility, and is effective inmaintaining a large voltage holding ratio at room temperature and alsoat a high temperature even after the device has been used for a longtime. A desirable ratio of the antioxidant is approximately 50 ppm ormore in order to obtain the advantages thereof and is approximately 600ppm or less in order to prevent the maximum temperature from beingdecreased and to prevent the minimum temperature from being increased. Amore desirable ratio is from approximately 100 ppm to approximately 300ppm.

Preferred examples of the ultraviolet light absorbent include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer having steric hindrance such as an amineis also desirable. A desirable ratio of the absorbent and the stabilizeris approximately 50 ppm or more for obtaining the advantages thereof andis approximately 10,000 ppm or less for preventing the maximumtemperature from being decreased and preventing the minimum temperaturefrom being increased. A more desirable ratio thereof ranges fromapproximately 100 ppm to approximately 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition to suit for a device of a guest host (GH) mode. Adesirable ratio of the dye ranges from approximately 0.01% toapproximately 10%. A defoaming agent such as dimethyl silicone oil ormethylphenyl silicone oil is mixed with the composition for preventingfoaming. A desirable ratio of the defoaming agent is approximately 1 ppmor more for obtaining the advantages thereof and is approximately 1,000ppm or less for preventing display failure from occurring. A moredesirable ratio thereof ranges from approximately 1 ppm to approximately500 ppm.

A polymerizable compound is mixed with the composition for applying thecomposition to a device having a PSA (polymer sustained alignment) mode.Preferred examples of the polymerizable compound include compoundshaving a polymerizable group, such as acrylate, methacrylate, vinyl,vinyloxy, propenyl ether, epoxy, vinylketone, oxetane and so forth.Particularly preferred examples thereof include derivatives of acrylateor methacrylate. A desirable ratio of the polymerizable group is fromapproximately 0.05% by weigh or more for obtaining the advantagesthereof, and is approximately 10% by weight or less for preventingdisplay failure from occurring. A more desirable ratio is fromapproximately 0.1 to approximately 2%. The polymerizable compound ispolymerized preferably in the presence of a suitable initiator, such asa photopolymerization initiator, under radiation of ultraviolet light.Suitable conditions for polymerization and a suitable type and asuitable amount of the initiator have been known by a skilled person inthe art and are disclosed in literatures. Examples of thephotopolymerization initiator suitable for radical polymerizationinclude Irgacure 651 (trade name), Irgacure 184 (trade name) andDarocure 1173 (trade name), all produced by Ciba Japan K.K. Thepolymerizable compound preferably contains a photopolymerizationinitiator in an amount of from approximately 0.1 to approximately 5% byweight, and particularly preferably contains a photopolymerizationinitiator in an amount of from approximately 1 to approximately 3% byweight.

Seventh, the preparation methods of the component compounds will beexplained. These compounds can be prepared by known methods. Thepreparation method will be exemplified below. The compounds (1-1) and(1-2) are prepared by the method disclosed in JP H10-237004 A/1998. Thecompound (2-1-1) is prepared by the method disclosed in JP S59-70624A/1984. The compound (2-2-1) is prepared by the method disclosed in JPS57-165328 A/1982. The compound (2-3-3) is prepared by the methoddisclosed in JP H2-237949 A/1990. The compounds (3-1) and (3-7) areprepared by the method disclosed in JP-T H2-503441 A/1990. Theantioxidant is commercially available. The compound (5), wherein n is 1,is available, for example, from Sigma-Aldrich, Inc. The compound (5),wherein n is 7, is prepared by the method disclosed in U.S. Pat. No.3,660,505.

The compounds for which preparation methods were not described above canbe prepared according to the methods described in Organic Syntheses(John Wiley & Sons, Inc.), Organic Reactions (John Wiley & Sons, Inc.),Comprehensive Organic Synthesis (Pergamon Press), New ExperimentalChemistry Course (Shin Jikken Kagaku Kouza) (Maruzen, Inc.), and soforth. The composition is prepared according to known methods using thecompounds thus obtained. For example, the component compounds are mixedand dissolved in each other by heating.

Last, use of the composition will be explained. Most of the compositionshave a minimum temperature of approximately −10° C. or less, a maximumtemperature of approximately 70° C. or more, and an optical anisotropyof approximately 0.07 to approximately 0.20. The device containing thecomposition has a large voltage holding ratio. The composition issuitable for an AM device. The composition is suitable especially for anAM device of a transmission type. The composition having an opticalanisotropy of approximately 0.08 to approximately 0.25 and furtherhaving an optical anisotropy of approximately 0.10 to approximately 0.30may be prepared by controlling ratios of the component compounds or bymixing other liquid crystal compounds. The composition can be used as acomposition having a nematic phase and as an optically activecomposition by adding an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for an AM device and a PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA, PSA and soforth. It is desirable to use the composition for an AM device having anIPS or VA mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device of a transmission type. It can be used foran amorphous silicon-TFT device or a polycrystal silicon-TFT device. Thecomposition is also usable for a nematic curvilinear aligned phase(NCAP) device prepared by microcapsulating the composition, and for apolymer dispersed (PD) device in which a three dimensional net-workpolymer is formed in the composition.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the invention and specificexamples provided herein without departing from the spirit or scope ofthe invention. Thus, it is intended that the invention covers themodifications and variations of this invention that come within thescope of any claims and their equivalents.

The following examples are for illustrative purposes only and are notintended, nor should they be interpreted to, limit the scope of theinvention.

EXAMPLES

When a sample was a composition, it was measured as it was, and theobtained value is described here. When a sample was a compound, a samplefor measurement was prepared by mixing 15% by weight of the compound and85% by weight of mother liquid crystals. A value of characteristic ofthe compound was calculated by extrapolating from a value obtained bymeasurement. Namely: extrapolated value=(value measured forsample−0.85×value measured for mother liquid crystals)/0.15. When asmectic phase (or crystals) was separated out at this ratio at 25° C., aratio of the compound and mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight), (1% by weight/99% by weight), respectively. Values for amaximum temperature, optical anisotropy, viscosity, and dielectricanisotropy of the compound were obtained by the extrapolation.

The composition of the mother liquid crystals is as shown below. All thepercentages for the composition are percentage by weight.

Measurement of the characteristics was carried out according to thefollowing methods. Most methods are described in the Standard ofElectric Industries Association of Japan, EIAJ ED-2521 A or those withsome modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. A temperaturewas measured when a part of the sample began to change from a nematicphase into an isotropic liquid. A higher limit of a temperature range ofa nematic phase may be abbreviated to “a maximum temperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in a glass vial and then kept in a freezer attemperatures of 0° C., −10° C., −20° C., −30° C., and −40° C. for tendays, respectively, and a liquid crystal phase was observed. Forexample, when the sample remained in a nematic phase at −20° C. andchanged to crystals or a smectic phase at −30° C., Tc was expressed as≦−20° C. A lower limit of a temperature range of a nematic phase may beabbreviated to “a minimum temperature.”

Viscosity (η; measured at 20° C., mPa·s): A viscosity was measured bymeans of an E-type viscometer.

Optical Anisotropy (refractive index an isotropy; Δn; measured at 25°C.): Measurement was carried out with an Abbe refractometer mounting apolarizing plate on an ocular using a light at a wavelength of 589 nm.The surface of a main prism was rubbed in one direction, and then asample was dropped on the main prism. Refractive index (n∥) was measuredwhen the direction of a polarized light was parallel to that of therubbing. Refractive index (n⊥) was measured when the direction of apolarized light was perpendicular to that of the rubbing. A value ofoptical anisotropy was calculated from the equation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δε; measured at 25° C.): A value of a dielectricanisotropy was calculated from the equation: Δε=ε∥−ε⊥. The values ofdielectric anisotropy (ε∥ and ε⊥) were measured in the following manner.

(1) Measurement of dielectric anisotropy (ε∥): A solution ofoctadecyltriethoxysilane (0.16 mL) dissolved in ethanol (20 mL) wascoated on a glass substrate having been well cleaned. The glasssubstrate was rotated with a spinner and then heated to 150° C. for 1hour. A sample was charged in a VA device having a distance (cell gap)of 4 μm between two sheets of the glass substrates, and the device wassealed with an adhesive capable of being cured with ultraviolet light.Sine waves (0.5 V, 1 kHz) were applied to the device, and after lapsingtwo seconds, a dielectric constant (ε∥) in the major axis direction ofthe liquid crystal molecule was measured.

(2) Measurement of dielectric anisotropy (ε⊥): Polyimide was coated on aglass substrate having been well cleaned. The glass substrate was baked,and the resulting orientation film was subjected to a rubbing treatment.A sample was charged in a TN device having a distance between two sheetsof the glass substrates of 9 μm and a twisted angle of 80°. Sine waves(0.5 V, 1 kHz) were applied to the device, and after lapsing twoseconds, a dielectric constant (ε⊥) in the minor axis direction of theliquid crystal molecule was measured.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. The light source was a halogen lamp. A sample was poured intoa VA device of a normally black mode, in which a cell gap between twoglass plates was 4 μm, and a rubbing direction was antiparallel, and thedevice was sealed with a UV curing adhesive. Voltage to be applied ontothe device (60 Hz, rectangular waves) was increased stepwise by 0.02 Vstarting from 0 V up to 20 V. During the stepwise increasing, the devicewas irradiated with light in a perpendicular direction, and an amount ofthe light passing through the device was measured. Voltage-transmissioncurve was prepared, in which a maximum amount of a light corresponded to100% transmittance, a minimum amount of a light corresponded to 0%transmittance. Threshold voltage is a value at 10% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was impressed andcharged with pulse voltage (60 microseconds at 5 V). Decreasing voltagewas measured for 16.7 milliseconds with High Speed Voltmeter and thearea A between a voltage curve and a horizontal axis in a unit cycle wasobtained. The area B was an area without decreasing. Voltage holdingratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement has a polyimide-alignment film and the cell gap betweentwo glass plates is 5 μm. A sample was poured into the device, and thenthe device was sealed with an adhesive which is polymerized by theirradiation of an ultraviolet light. The TN device was impressed andcharged with pulse voltage (60 microseconds at 5 V). Decreasing voltagewas measured for 16.7 milliseconds with High Speed Voltmeter and thearea A between a voltage curve and a horizontal axis in a unit cycle wasobtained. The area B was an area without decreasing. Voltage holdingratio is a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): A voltage holdingratio was measured after irradiating with ultraviolet light to evaluatestability to ultraviolet light. A composition having large VHR-3 has alarge stability to ultraviolet light. A TN device used for measurementhas a polyimide-alignment film and the cell gap is 5 μm. A sample waspoured into the device, and then the device was irradiated with lightfor 20 minutes. The light source was a superhigh voltage mercury lampUSH-500D (produced by Ushio, Inc.), and the distance between the deviceand the light source is 20 cm. In measurement of VHR-3, a decreasingvoltage is measured for 16.7 milliseconds. VHR-3 is desirably 90% ormore, and more desirably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A voltage holdingratio was measured after heating an TN device having a sample pouredtherein in a constant-temperature bath at 80° C. for 500 hours toevaluate stability to heat. A composition having large VHR-4 has a largestability to heat. In measurement of VHR-4, a decreasing voltage ismeasured for 16.7 milliseconds.

Response Time (r; measured at 25° C.; ms): Measurement was carried outwith LCD Evaluation System Model LCD-5100 made by Otsuka ElectronicsCo., Ltd. Light source is a halogen lamp. Low-pass filter was set at 5kHz. A sample was poured into a VA device of a normally black mode, inwhich a cell gap between two glass plates was 4 μm, and a rubbingdirection was antiparallel, and the device was sealed with a UV curingadhesive. Rectangle waves (60 Hz, 10 V, 0.5 seconds) were applied to thedevice. During application, the device was irradiated with light in aperpendicular direction, and an amount of the light passing through thedevice was measured. A maximum amount of a light corresponds to 100%transmittance, and a minimum amount of a light corresponds to 0%transmission. Response time is a period of time required for the changein transmittance from 90% to 10% (fall time: ms).

Specific Resistance (ρ; measured at 25° C.; Ωcm): 1.0 mL of a sample wascharged in a vessel equipped with electrodes. A direct current voltageof 10 V was impressed to the vessel, and after lapsing 10 second fromthe impress of voltage, the direct electric current was measured. Thespecific resistance was calculated by the equation: (specificresistance)={(voltage)×(electric capacity of vessel)}/{(directcurrent)×(dielectric constant of vacuum)}.

Gas Chromatographic Analysis: A Gas Chromatograph Model GC-14B made byShimadzu was used for measurement. The carrier gas was helium (2milliliters per minute). An evaporator and a detector (FID) were set upat 280° C. and 300° C., respectively. Capillary column DB-1 (length 30meters, bore 0.32 millimeters, film thickness 0.25 micrometers,dimethylpolysiloxane as stationary phase, no polarity) made by AgilentTechnologies, Inc. was used for the separation of the componentcompound. After the column had been kept at 200° C. for 2 minutes, itwas further heated to 280° C. at the rate of 5° C. per minute. A samplewas prepared in an acetone solution (0.1% by weight), and 1 microliterof the solution was injected into the evaporator. The recorder used wasa Chromatopac Model C-R5A made by Shimadzu or its equivalent. Gaschromatogram obtained showed a retention time of a peak and a peak areacorresponding to the component compound.

Solvents for diluting the sample may also be chloroform, hexane, and soforth. The following capillary columns may also be used for theseparation of the component compound: HP-1 made by Agilent TechnologiesInc. (length 30 meters, bore 0.32 millimeters, film thickness 0.25micrometers), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeters, film thickness 0.25 micrometers), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeters, filmthickness 0.25 micrometers). In order to prevent compound peaks fromoverlapping, a capillary column CBP1-M50-025 (50 meters, bore 0.25millimeters, film thickness 0.25 micrometers) made by ShimadzuCorporation may be used.

The ratios of the liquid crystal compounds contained in the compositioncan also be calculated in the following manner. A liquid crystalcompound can be detected by gas chromatography. An area ratio of peakson a gas chromatogram corresponds to a ratio (molar number) of liquidcrystal compounds. In the case where the aforementioned capillarycolumns are used, correction coefficients of the liquid crystalcompounds can be regarded as 1. Accordingly, the ratio (% by weight) ofliquid crystal compounds is calculated from the area ratio of peaks.

The invention will be explained in detail by way of Examples. Theinvention is not limited by the Examples described below. The compoundsdescribed in the Comparative Examples and the Examples are expressed bythe symbols according to the definition in Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. The parenthesized numbernext to the symbolized compounds in the Examples corresponds to thenumber of the desirable compound. The symbol (-) means other liquidcrystal compound. A ratio (percentage) of a liquid crystal compound ispercentage by weight (% by weight) based on the total weight of liquidcrystal compounds, and the liquid crystal compositions further containimpurities. Last, the characteristics of the composition are summarized.

TABLE 3 Method of Description of Compound using Symbols R-(A₁)-Z₁- . . .-Z_(n)-(A_(n))-R′ (1) Left Terminal Group R- Symbol C_(n)H_(2n+1)— n-C_(n)H_(2n+1)O— nO- C_(m)H_(2m+1)OC_(n)H_(2n)— mOn- CH₂═CH— V-C_(n)H_(2n+1)—CH═CH— nV- CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF- CF₂═CH—C_(n)H_(2n)—VFFn- (2) Right Terminal Group -R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) -On —CH═CH₂ -V —CH═CH—C_(n)H_(2n+1) -Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ -VFF —COOCH₃ -EMe (3) Bonding Group -Zn-Symbol —OC_(n)H_(2n)O— OnO —C_(n)H_(2n)— n —COO— E —CH═CH— V —CH₂O— 1O—OCH₂— O1 —SiH₂— Si (4) Ring structure -An- Symbol

H

ch

B

B(2F)

B(3F)

B(2F,3F)

B(2F,3Cl)

B(2Cl,3F)

B(2F,3CF2H) (5) Example of Description Example 1 3-HO2OB(2F,3F)-O2

Example 2 3-HHO2OB(2F,3F)-4

Example 3 5-HBB(3F)B-3

Example 4 3-HBB(2F,3F)-O2

Comparative Example 1

A composition corresponding to Example 22 of JP 2007-002132 A/2007 wasprepared and measured for characteristics by the aforementioned manners.The basis is that the composition contains the compound (1-2-9) and acompound analogous to the compound (1-2), and has the minimum viscosity(η). The components and characteristics of the composition were asfollows.

3-HB(2F)-O2 (—) 10% 3-HB(3F)-O2 (—) 10% 3-HHB(2F)-1 (—) 4% 3-HHB(2F)-O2(—) 4% 3-HHB(3F)-1 (—) 4% 3-H1OB(2F)-O2 (—) 14% 3-HV1OB(2F,3F)-O2 (—) 6%3-HO1VB(2F,3F)-O2 (—) 6% 3-BV1OB(2F,3F)-O1 (—) 1% 5-BVO1B(2F,3F)-1 (—)1% 2-H4HB(2F,3F)-O2 (—) 1% 2-HO2OHB(2F,3F)-O1 (1-2-1) analog 1%2-HV1OHB(2F,3F)-O2 (—) 9% 3-HO1VHB(2F,3F)-O2 (—) 9% 3-HHVB(2F,3F)-O2 (—)1% 2-HHV1OB(2F,3F)-1 (—) 8% 3-HHO1VB(2F,3F)-1 (—) 8%3-HB(2F)V1OB(2F,3CF2H)-O2 (—) 1% 2-BH4B(2F,3F)-O1 (—) 1%3-BHO2OB(2F,3F)-1 (1-2-9) 1% NI = 67.3° C.; Tc ≦ −20° C.; Δn = 0.096; Δε= −4.1; η = 22.0 mPa · s; VHR-1 = 99.0%

Example 1

The composition of Example 1 has a high maximum temperature of a nematicphase, a small viscosity and a large refractive index anisotropy ascompared to Comparative Example 1.

3-HHO2OB(2F,3F)-O2 (1-2-1) 6% 5-HHO2OB(2F,3F)-O2 (1-2-1) 7%3-HBO2OB(2F,3F)-O2 (1-2-5) 7% 5-HBO2OB(2F,3F)-O2 (1-2-5) 7%3-BBO2OB(2F,3F)-O2 (1-2-13) 7% 5-BBO2OB(2F,3F)-O2 (1-2-13) 6% 2-HH-3(2-1-1) 6% 3-HH-5 (2-1-1) 7% 3-HH-V1 (2-1-1) 10% V2-BB-1 (2-1-3) 14%1V2-BB-1 (2-1-3) 14% 3-HHB-O1 (2-2-1) 4% 3-HHEBH-3 (2-3-4) 5% NI = 70.4°C.; Tc ≦ −20° C.; Δn = 0.126; Δε = −2.7; η = 20.0 mPa · s; VHR-1 =99.1%; VHR-2 = 98.3%; VHR-3 = 98.1%

Example 2

The composition of Example 2 has a high maximum temperature of a nematicphase, a small viscosity and a large refractive index anisotropy ascompared to Comparative Example 1.

3-HO2OB(2F,3F)-O2 (1-1-1) 5% 3-HBO2OB(2F,3F)-O2 (1-2-5) 7%5-HBO2OB(2F,3F)-O2 (1-2-5) 7% 2-HH-3 (2-1-1) 5% 3-HH-V1 (2-1-1) 5%3-HB-O1 (2-1-2) 5% V2-BB-1 (2-1-3) 15% 1V2-BB-1 (2-1-3) 12% 5-HBB(3F)B-2(2-3-3) 5% 3-HHB(2F,3F)-O2 (3-7-1) 8% 5-HHB(2F,3F)-O2 (3-7-1) 8%2-HBB(2F,3F)-O2 (3-9-1) 5% 3-HBB(2F,3F)-O2 (3-9-1) 8% 2-H2H-3 (—) 5% NI= 76.1° C.; Tc ≦ −20° C.; Δn = 0.126; Δε = −3.1; η = 20.0 mPa · s

Example 3

The composition of Example 3 has a high maximum temperature of a nematicphase, a small viscosity and a large refractive index anisotropy ascompared to Comparative Example 1.

5-HO2OB(2F,3F)-O2 (1-1-1) 5% 3-HO2OB(2F,3Cl)-O2 (1-1-2) 3%3-HHO2OB(2F,3F)-O2 (1-2-1) 5% 3-BBO2OB(2F,3F)-O2 (1-2-13) 8% 3-HH-5(2-1-1) 10% 3-HH-V (2-1-1) 15% V2-BB-1 (2-1-3) 11% 1V2-BB-1 (2-1-3) 6%3-HB(3F)BH-3 (2-3-2) 3% 5-HBB(3F)B-3 (2-3-3) 5% 3-H2B(2F,3F)-O2 (3-4-1)8% 3-HBB(2F,3F)-O2 (3-9-1) 5% V-HBB(2F,3F)-O2 (3-9-1) 8%V2-HBB(2F,3F)-O2 (3-9-1) 5% 3-HBB(2F,3Cl)-O2 (3-10-1) 3% NI = 70.4° C.;Tc ≦ −20° C.; Δn = 0.125; Δε = −2.7; η = 19.8 mPa · s

Example 4

3-HO2OB(2Cl,3F)-O2 (1-1-3) 3% 3-HO2OB(2Cl,3Cl)-O2 (1-1-4) 4%5-HHO2OB(2F,3F)-O2 (1-2-1) 6% 3-BBO2OB(2F,3F)-O2 (1-2-13) 3% 3-HH-V1(2-1-1) 12% V2-BB-1 (2-1-3) 15% 3-HHB-O1 (2-2-1) 5% 3-HBB-2 (2-2-2) 8%1V-HBB-2 (2-2-2) 8% 2-BB(3F)B-3 (2-2-3) 5% 1O1-HBBH-4 (—) 3%3-HB(2F,3F)-O2 (3-1-1) 8% 3-BB(2F,3F)-O2 (3-3-1) 5% 5-BB(2F,3F)-O2(3-3-1) 5% 3-HH1OB(2F,3F)-O2 (3-12-1) 10% NI = 72.6° C.; Tc ≦ −20° C.;Δn = 0.128; Δε = −2.7; η = 19.4 mPa · s

Example 5

3-BO2OB(2F,3F)-O2 (1-1-5) 3% 3-HHO2OB(2F,3F)-O2 (1-2-1) 8%3-BBO2OB(2F,3F)-O2 (1-2-13) 5% 3-HH-V (2-1-1) 11% 3-HH-V1 (2-1-1) 11%3-HB-O1 (2-1-2) 5% V-HHB-1 (2-2-1) 7% 3-HBB-2 (2-2-2) 6% 1V-HBB-2(2-2-2) 6% 2-BB(3F)B-3 (2-2-3) 3% V-HB(2F,3F)-O2 (3-1-1) 6%3-BB(2F,3F)-O2 (3-3-1) 5% 5-BB(2F,3F)-O2 (3-3-1) 5% 3-HBB(2F,3F)-O2(3-9-1) 8% V-HBB(2F,3F)-O2 (3-9-1) 3% V2-HBB(2F,3F)-O2 (3-9-1) 8% NI =77.7° C.; Tc ≦ −20° C.; Δn = 0.127; Δε = −2.7; η = 19.9 mPa · s

Example 6

3-HO2OB(2F,3F)-O2 (1-1-1) 11% 3-BO2OB(2F,3Cl)-O2 (1-1-6) 2%3-BO2OB(2Cl,3F)-O2 (1-1-7) 2% 3-HH-5 (2-1-1) 4% 3-HH-V1 (2-1-1) 10%V2-BB-1 (2-1-3) 15% 1V2-BB-1 (2-1-3) 10% 3-HHEH-3 (2-2-4) 5%5-HBB(3F)B-3 (2-3-3) 5% 2-HBB(2F,3F)-O2 (3-9-1) 7% 3-HBB(2F,3F)-O2(3-9-1) 7% V-HBB(2F,3F)-O2 (3-9-1) 7% V2-HBB(2F,3F)-O2 (3-9-1) 7%3-HH1OB(2F,3F)-O2 (3-12-1) 8% NI = 75.0° C.; Tc ≦ −30° C.; Δn = 0.129;Δε = −3.0; η = 20.0 mPa · s

Example 7

3-BO2OB(2Cl,3Cl)-O2 (1-1-8) 3% 5-HHO2OB(2F,3F)-O2 (1-2-1) 7%3-BBO2OB(2F,3F)-O2 (1-2-13) 7% 2-HH-3 (2-1-1) 8% 3-HH-V1 (2-1-1) 10%5-HH-O1 (2-1-1) 3% V2-BB-1 (2-1-3) 15% 1V2-BB-1 (2-1-3) 7% 5-HBB(3F)B-3(2-3-3) 5% 5-HB(2F,3Cl)-O2 (3-2-1) 5% 3-B2B(2F,3F)-O2 (3-6-1) 3%V-HHB(2F,3F)-O2 (3-7-1) 3% V2-HHB(2F,3F)-O2 (3-7-1) 3% 3-HBB(2F,3F)-O2(3-9-1) 8% V2-HBB(2F,3F)-O2 (3-9-1) 8% 3-HH1OB(2F,3F)-O2 (3-12-1) 5% NI= 72.2° C.; Tc ≦ −20° C.; Δn = 0.128; Δε = −3.1; η = 19.9 mPa · s

Example 8

3-HHO2OB(2F,3F)-O2 (1-2-1) 8% 5-HHO2OB(2F,3F)-O2 (1-2-1) 8%3-HBO2OB(2F,3F)-O2 (1-2-5) 4% 3-HH-V1 (2-1-1) 10% 5-HB-3 (2-1-2) 3%V2-BB-1 (2-1-3) 15% 1V2-BB-1 (2-1-3) 7% 3-HHB-1 (2-2-1) 3% V2-HHB-1(2-2-1) 5% V2-BB(3F)B-1 (2-2-3) 5% 5-HBBH-3 (2-3-1) 3% 3-BB(2F,3F)-O2(3-3-1) 5% 3-HHB(2F,3F)-1 (3-7-1) 3% 5-HHB(2F,3Cl)-O2 (3-8-1) 3%2-HBB(2F,3F)-O2 (3-9-1) 5% 3-HBB(2F,3F)-O2 (3-9-1) 5% 5-HH2B(2F,3F)-O2(3-11-1) 3% 3-HH1OB(2F,3F)-O2 (3-12-1) 5% NI = 85.2° C.; Tc ≦ −20° C.;Δn = 0.130; Δε = −2.9; η = 19.3 mPa · s

Example 9

3-HHO2OB(2F,3F)-O2 (1-2-1) 8% 5-HHO2OB(2F,3F)-O2 (1-2-1) 8% 3-HH-V(2-1-1) 8% V2-BB-1 (2-1-3) 15% 1V2-BB-1 (2-1-3) 7% V2-HHB-1 (2-2-1) 5%2-BB(3F)B-3 (2-2-3) 7% 1-BB(3F)B-2V (2-2-3) 7% V-HB(2F,3F)-O2 (3-1-1) 7%5-HB(2F,3Cl)-O2 (3-2-1) 4% V-HHB(2F,3F)-O2 (3-7-1) 7% V2-HHB(2F,3F)-O2(3-7-1) 7% 3-HHB(2F,3Cl)-O2 (3-8-1) 5% 3-HH1OB(2F,3F)-O2 (3-12-1) 5% NI= 75.8° C.; Tc ≦ −20° C.; Δn = 0.128; Δε = −2.8; η = 19.2 mPa · s

Example 10

3-HHO2OB(2F,3F)-O2 (1-2-1) 8% 5-HHO2OB(2F,3F)-O2 (1-2-1) 8% 3-HH-4(2-1-1) 5% 3-HH-V (2-1-1) 5% V2-BB-1 (2-1-3) 12% 1V2-BB-1 (2-1-3) 10%V-HHB-1 (2-2-1) 4% 2-BB(3F)B-3 (2-2-3) 6% V2-BB(3F)B-1 (2-2-3) 6%V-HB(2F,3F)-O2 (3-1-1) 3% 5-HB(2F,3Cl)-O2 (3-2-1) 3% V-HHB(2F,3F)-O2(3-7-1) 5% V2-HHB(2F,3F)-O2 (3-7-1) 5% 5-HHB(2F,3Cl)-O2 (3-8-1) 5%3-HBB(2F,3F)-O2 (3-9-1) 5% 3-HH1OB(2F,3F)-O2 (3-12-1) 5% NI = 75.6° C.;Tc ≦ −20° C.; Δn = 0.127; Δε = −2.9; η = 19.5 mPa · s

1. A liquid crystal composition having a negative dielectric anisotropycomprising two components, wherein the first component is at least onecompound selected from the group consisting of compounds represented byformulas (1-1) and (1-2), and the second component is at least onecompound selected from the group consisting of compounds represented byformulas (2-1) to (2-3):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; R³ andR⁴ are each independently alkyl having 1 to 12 carbons or alkenyl having2 to 12 carbons, provided that in the alkyl and the alkenyl, arbitraryhydrogen may be replaced by fluorine, and arbitrary —CH₂— may bereplaced by —O—; X¹ and X² are each independently fluorine or chlorine;ring A, ring B, ring C and ring D are each independently1,4-cyclohexylene or 1,4-phenylene; ring E and ring G are eachindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenyleneor 3-fluoro-1,4-phenylene; ring F is 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; and Z′ is a single bond or carbonyloxy. 2.The liquid crystal composition of claim 1, wherein the first componentis a mixture of at least one compound selected from the group consistingof compounds represented by formula (1-1) and at least one compoundselected from the group consisting of compounds represented by formula(1-2), and the second component is at least one compound selected fromthe group consisting of compounds represented by formula (2-1).
 3. Theliquid crystal composition of claim 1, wherein the second component is amixture of at least one compound selected from the group consisting ofcompounds represented by formula (2-1) and at least one compoundselected from the group consisting of compounds represented by formula(2-2).
 4. The liquid crystal composition of claim 1, wherein the secondcomponent is a mixture of at least one compound selected from the groupconsisting of compounds represented by formula (2-1) and at least onecompound selected from the group consisting of compounds represented byformula (2-3).
 5. The liquid crystal composition of claim 1, wherein thesecond component is a mixture of at least one compound selected from thegroup consisting of compounds represented by formula (2-2) and at leastone compound selected from the group consisting of compounds representedby formula (2-3).
 6. The liquid crystal composition of claim 1, whereina ratio of the first component is from approximately 5% by weight toapproximately 50% by weight, and a ratio of the second component is fromapproximately 35% by weight to approximately 70% by weight, based on thetotal weight of the liquid crystal composition.
 7. The liquid crystalcomposition of claim 1, wherein the composition further comprises atleast one compound selected from the group consisting of compoundsrepresented by formula (3) as a third component:

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons; ring Iis independently 1,4-cyclohexylene or 1,4-phenylene; Z² is a singlebond, ethylene, carbonyloxy or methyleneoxy; X³ and X⁴ are eachindependently fluorine or chlorine; and n is 1 or
 2. 8. The liquidcrystal composition of claim 7, wherein the third component is at leastone compound selected from the group consisting of compounds representedby formulas (3-1) to (3-12):

wherein R¹ and R² are each independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons.
 9. Theliquid crystal composition of claim 7, wherein the third component is amixture of at least one compound selected from the group consisting ofcompounds represented by formula (3-1) and at least one compoundselected from the group consisting of compounds represented by formula(3-7).
 10. The liquid crystal composition of claim 7, wherein the thirdcomponent is a mixture of at least one compound selected from the groupconsisting of compounds represented by formula (3-1) and at least onecompound selected from the group consisting of compounds represented byformula (3-9).
 11. The liquid crystal composition of claim 7, whereinthe third component is a mixture of at least one compound selected fromthe group consisting of compounds represented by formula (3-4) and atleast one compound selected from the group consisting of compoundsrepresented by formula (3-9).
 12. The liquid crystal composition ofclaim 7, wherein a ratio of the first component is from approximately 5%by weight to approximately 50% by weight, a ratio of the secondcomponent is from approximately 35% by weight to approximately 70% byweight, and a ratio of the third component is from approximately 5% byweight to approximately 40% by weight, based on the total weight of theliquid crystal composition.
 13. The liquid crystal composition of claim1, wherein the composition has a maximum temperature of a nematic phaseof approximately 70° C. or more, an optical anisotropy (25° C.) at awavelength of 589 nm of approximately 0.08 or more, and a dielectricanisotropy (25° C.) at a frequency of 1 kHz of approximately −2 or less.14. A liquid crystal display device that includes the liquid crystalcomposition of claim
 1. 15. The liquid crystal display device of claim14, wherein the liquid crystal display device has an operation mode of aVA mode or an IPS mode, and has a driving mode of an active matrix mode.16. The liquid crystal display device of claim 14, wherein the liquidcrystal display device has an operation mode of a PSA mode, and has adriving mode of an active matrix mode.